Early on the morning of Sunday, Dec. 11, 2005, a tremendous explosion rocked southern England. The blast, centered on Buncefield Depot, an oil storage terminal in Hertfordshire that supplied fuel to Heathrow airport, registered 2.4 on the Richter scale, and was reportedly heard as far away as France and The Netherlands.

Forty-three people were injured, 227 schools were closed and buildings were damaged five miles away. Two thousand people were temporarily displaced amid concerns over possible health implications caused by the smoke plume, which could be seen from space, and which eventually spread to France and Spain.

The explosion was ruled accidental, but that didn’t let the company managing the depot, Total UK Ltd, off the hook. In May 2008, a High Court judge ruled that Total UK and its partner, Hertfordshire Oil Storage Ltd, were negligent and responsible for the accident. The companies admitted negligence, but denied liability, claiming they didn’t realize how much damage they could cause. That didn’t fly, and in March 2009, the High Court found Total UK, which had sole responsibility for filling the tanks, liable for the blast, leaving the company facing damage claims of around £700 million.

High profile cases such as this one, and the BP Texas City refinery explosion—which killed 15 workers and injured 170 more in March 2005 and has already cost BP $50 million in fines and upwards of $1.6 billion in compensation—have heightened awareness of safety standards, and led to a sharp increase in demand for Safety Instrumented Systems (SIS).

An increased feeling of vulnerability following incidents such as these contributed to ARC Advisory Group Inc., Dedham, Mass., predicting the SIS market will grow at a compound annual growth rate of about 12 percent to reach $2.5 billion in 2012, despite the economic downturn.

According to ARC Vice President Asish Ghosh, numerous factors have combined to drive this growth, including increased demand for oil and gas to fuel economic growth in emerging markets such as China and India, greater environmental awareness, and increased awareness of safety standards such as IEC 61508, IEC 61511 (both promulgated by the International Electrotechnical Commission), and ANSI/ISA84, promulgated by the American National Standards Institute and International Society of Automation.

Safety is complicated

However, there is more to becoming compliant with safety standards than simply writing a request for proposal (RFP) and hiring a vendor. One of the greatest challenges with implementing safety standards in your production facility is simply knowing which standards apply to you and how.

For the average control engineer, the world of safety standards is a complicated and confusing morass that can vary widely by geographic region. Standards in Europe are not necessarily the same as those in the United States, Canada, Latin America or Asia. In fact, a multinational organization may have to incorporate two or three different standards for the same thing into its corporate standard.

What’s more, being standards-compliant is a moving target. Once you get your plant up to snuff, you have to keep up with the changes that will come with the inevitable revision that occurs every five or so years.

For example, a 2006 update to the International Organization for Standardization’s ISO 13849, which provides safety requirements and guidance on the principles for the design and integration of safety-related parts of control systems, including any software, will come into effect in Europe by October. Other significant changes are coming, demanding risk assessments be completed and incorporated into SIS designs, and that end-users take a lifecycle approach to their safety systems.

Other critical updates involve the demand for a risk assessment. Says Juergen Bukowski, program manager, Safety, for automation components vendor Sick Inc., in Minneapolis, “Every machine builder and end-user has to make sure a safety assessment is done. End-users and machine builders have to work together to make sure the assessment is done on a particular line, machine or production plan. That is one big change.

“Second: once you’ve done the risk assessment, you will have somewhere where the risk is still too high and you have to take protective measures and integrate them into your machine control. But what constitutes ‘acceptable risk?’ The standards give you guidelines that help quantify the risk. That is something that is pretty new for machine builders and end-users.”

Two-layer safety

There are two layers to the whole safety field, explains Bukowski. The regulatory layer is based on laws, and essentially says that companies are responsible for ensuring that their operations don’t endanger the public, for providing a ...